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KEY POINTS

Pulmonary stenosis and atresia refer to congenital narrowing or complete occlusion of the right ventricular outflow tract respectively.

It may occur in isolation or as part of Williams or Noonan syndrome, or secondary to teratogenic exposure such as congenital rubella syndrome.

Prenatal diagnosis relies upon identification of asymmetry in ventricular size, right atrial enlargement, thickening of the pulmonary valve and Doppler abnormalities across the pulmonary valve.

Obstetric management generally does not need to be changed following this diagnosis, although in cases of critical pulmonary stenosis or atresia, delivery should occur in a controlled manner in a center with pediatric cardiology backup and ability to provide prostaglandin infusion.

Neonatal management depends on the pressure gradient across the pulmonary valve, with invasive intervention reserved generally for those cases with pressure gradients greater than 30 to 50 mm Hg.

CONDITION

The term pulmonary stenosis refers to narrowing of the right ventricular outflow tract; pulmonary atresia implies complete occlusion of the right ventricular outflow tract. Pulmonary atresia, when associated with an intact ventricular septum, is also considered as a hypoplastic right ventricle and is described in detail in Chapter 47. Pulmonary atresia with coexistent ventricular septal defect is generally considered part of the spectrum of tetralogy of Fallot and is described in detail in Chapter 52. Pulmonary stenosis usually results from fusion of the three cusps of the pulmonary valve. Other causes of pulmonary stenosis include narrowing of the infundibular portion of the right ventricular outflow tract, hypoplasia of the pulmonary artery, or pulmonary valve dysplasia, in which the valve leaflets are thickened and immobile. Pulmonary artery hypoplasia and supravalvar pulmonary stenosis may occur in association with Williams syndrome or with congenital rubella or toxoplasmosis (Gutgesell, 1990; Rhodes et al., 2008). Supravalvar pulmonary valve stenosis may also occur in association with Noonan syndrome, which has a phenotype similar to Turner syndrome, but a normal karyotype (Mendez and Opitz, 1985; Rhodes et al., 2008). Approximately 60% of cases of Noonan syndrome will have a dysplastic pulmonary valve (Bashore, 2007).

Pulmonary stenosis may lead to right ventricular hypertrophy, a decrease in right ventricular chamber size, and poststenotic dilation of the pulmonary artery (Romero et al., 1988). Poststenotic dilation of the pulmonary artery is rarely present in utero and usually takes several months of neonatal life to develop (Gutgesell, 1990). In cases of critical pulmonary stenosis, hypoplasia of the right ventricular cavity may occur together with hypertrophy of the ventricular wall and dilation of the right atrium. In such cases, neonates usually have an interatrial communication through either a patent foramen ovale or a secundum atrial septal defect. Other associated cardiac defects that may be seen with pulmonary stenosis ...